After all steps above:
Plug your USB drive into the bottom port (the one closest to the edge or rubber feet). wii usb loader gx usb device not initialized repack
Even if your USB drive is detected, your games won't show up if they're in the wrong location or named incorrectly. After all steps above: Plug your USB drive
In some cases, the error message appears not because the drive is undetected, but because the loader reads a corrupted game file and throws a generic error. it will never initialize.
Repack note: Some repacks force USB Port 0 specifically. If your drive is in Port 1, it will never initialize.